Known package boxing machines comprise an initial grouping unit where a number of lines of successive adjacent individual packages are formed; and a final grouping unit where a number of lines of packages are superimposed to form groups of packages. Downstream from the final grouping unit, a packing unit packs each group of packages into a respective cardboard box.
Known grouping units work well, but have the major drawback of not being very flexible. That is, changing the format of the packages to be grouped or the conformation of the group of packages involves changing several component parts on the packing unit. This is a particularly painstaking, time-consuming job requiring skilled labour, in that, in addition to removing parts and assembling new ones, the packing unit as a whole must be set up to make sure the new parts interact properly with the rest of the unit. This lack of flexibility is an increasingly important issue in view of the general market tendency towards small production lots with frequent changeovers.
Patent Application EP2364916A1 describes a grouping unit for forming a line of products on a packing machine, and which comprises: a first feed conveyor for feeding a succession of products along a grouping path at a first speed; a first compacting conveyor for feeding a first compacting member downstream from the first feed conveyor, along the grouping path, and ahead of the lead product in the line, at a second speed slower than the first, so as to slow down the lead product and compact the intermediate products in the line against the lead product; and a second compacting conveyor for feeding a second compacting member downstream from the first feed conveyor, along the grouping path, and behind the last product in the line, at a third speed higher than the first, so as compact the last product against the intermediate products in the line.
The grouping unit described in Patent Application EP2364916A1 has several drawbacks by requiring an additional auxiliary compacting conveyor, which feeds along the other two compacting conveyors an auxiliary compacting member, which is also movable perpendicular to the grouping path and, for a certain length of time, performs the functions of the first compacting member. The various movements performed by the auxiliary compacting member make the auxiliary compacting conveyor extremely complicated to produce and control.